Professors at some of the nation’s top law schools say this practice undermines public trust in courts and gives the appearance that defendants with enough money get preferential treatment and can buy their way out of trouble. They say such payments violate a basic ethical principle: Monetary contributions or payments resulting from plea bargains should not in any way benefit or appear to benefit the offices of the prosecutor, the judge or police involved in the prosecution.

“It is clearly unethical and a violation of the Constitution,” said legal ethics expert Monroe H. Freedman, a professor at Hofstra University Law School in Hempstead, N.Y. Like other experts contacted for this story, Freedman cautioned he was not commenting about any specific case.